Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
This problem does not exist in MSP mode since all CLAV information is gathered in one cell
time.
2.4.2.2.2 TDM and the Basic 2 Level Priority Algorithm
When TDM is enabled, (refer to section 7.2.10 UTOPIA_CONFIG and to section 7.2.12
UT_ENABLE for configuring the TDM Pool) another level is added on top of the Basic 2 Level
Priority Algorithm. The TDM table has primary service priority if the UTOPIA interface is con-
figured to use the TDM feature. Each cell time, the TDM pointer is advanced through the TDM
Pool in a round-robin fashion. When a PHY is pointed to and a cell is present in the QEngine for
the PHY, it will be selected. If a PHY is selected and a cell is NOT present in the QEngine for the
PHY, the selection process is deferred to the Basic 2 Level Priority Algorithm so that the cell time
is not wasted. The TDM table is most useful when configurations require uniformally distributed
bandwidths, such as 4xOC3 configurations. In the event that the TDM bit is not set in the
UTOPIA_CONFIG then the servicing algorithm reduces to the Basic 2 level Priority encoding
scheme consisting of 1, 2 and 3 above.
The Receive side of the QRT operates in the same fashion as the Transmit side with the exception
of the Stale Priority level since there is no Watchdog present in the Receive side.
The UTOPIA Level 2 specification is not designed to support oversubscription due to its lack of
multi-priority cell presence indications. The QRT interface assumes this is the case in order to
operate correctly.
2.4.2.3 Independently Configurable Interfaces
The receive and transmit sides of the UTOPIA interface are independently configurable for either
single-PHY OC-12 or multi-PHY operation. The RX_OC_12C_MODE, TX_OC_12C_MODE,
and UTOPIA_2 bits (refer to section 7.2.11 “UTOPIA_CONFIG” starting on page 117) configure
the device for such operation. This allows versatility in the types of PHY environments that can
be supported (for example, environments that contain high-speed, single-PHY devices can be
supported, as well as environments in which the QRT must perform single-chip, multi-PHY to
high-speed, single-PHY muxing operations). This versatility is particularly helpful when interfac-
ing to the PMC-Sierra, Inc. PM7322 RCMP-800 Operations, Administration, and Maintenance
(OAM) processor, since the output of that device has an interface similar to a single-PHY SAT-
URN interface.
2.4.2.4 Output Channel Number Insertion
The transmit side of the UTOPIA can be configured to insert the QRT output channel identifier in
the HEC/UDF field of outgoing cells. The output channel identifier is a value used by the QRT
transmit portion to identify cells of a particular cell stream as they come in from the fabric. Inser-
tion is configured by means of setting the UTOPIA_CONFIG(7) register. If the configuration bit
is set to 0, the UTOPIA inserts a value of FFFFh in the HEC/UDF field. The transmit UTOPIA
does not calculate the HEC for outgoing cells.
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PMC [ PMC-SIERRA, INC ]
